A ZDNet analysis of parliamentarian spending on telecommunications shows that backbenchers are racking up big bills using their mobile phones while overseas.

Parliamentary entitlements, particularly around travel entitlements, have been in sharp focus of late, with MPs from both the Liberal party and the Labor party being forced to pay back money for trips that had been charged to the taxpayer, but have since been discovered to have been for weddings, ski trips, or other non-work-related events.

But as part of their entitlements, MPs can also claim the cost of their office phones and mobile phones, and the high cost of using their phones while overseas.

The costs for ministers are kept separate from the general entitlements, so it is understandable that their expenses are often lower than those of backbenchers, but aside from then-opposition leader Tony Abbott, who racked up an AU$33,000 bill for telecommunications in six months, most MPs were below AU$10,000.

There are a number of MPs who went way over, however.

Now-retired Liberal backbench MP Barry Haase travelled to Canada, Mongolia, and the US in the last six months of 2012 on study trips, and in addition to the AU$91,066 he charged to the taxpayer for those trips, he also accrued $32,712 in global roaming charges on those trips between August and September that were charged back to the taxpayer. His bill was higher than any other MP listed.

Before Kevin Rudd returned to the Labor leadership in June 2013, he spent over a year on the backbench, a lot of which was actually spent overseas. The former prime minister appears to have been very busy on his phone in that time, managing to accrue AU$19,126 in global roaming charges between July and December 2012.

In his declarations, he mentioned only a trip between July and August in Sweden, Canada, and the US, but a review of speeches show that Rudd also visited Beijing, Singapore, and Qatar. Rudd's interest register shows that he also visited Paris, New Delhi, Mumbai, and Berlin on the dime of corporations, foreign governments, or universities.

Greens Senator Sarah Hanson-Young went to Indonesia for just three days in July 2012, and charged back AU$3,905 in roaming charges to the taxpayer in early August.

Labor Senator Ursula Stephens went to Ireland on a study trip in November 2012, and charged back AU$1,784 to the taxpayer in roaming charges for that trip, but she also spent an additional AU$3,517 in roaming charges that were not related to any parliamentary trip, and were not declared on her interests register.

Much of the debate over travel expenses has focused on whether an event attended by an MP is directly related to their work, with many MPs repaying costs associated with events that were deemed not to be work related. It is unclear whether roaming costs associated with overseas travel not related directly to work being done by an MP would also fall into this category. There is already precedent for an MP repaying global roaming charges.

After initially charging the taxpayer over AU$13,000 for global roaming charges accrued in the second half of 2011, now-Communications Minister Malcolm Turnbull paid back the money to the government, and was left to negotiate his bill with Telstra.

It comes as the telcos have worked to reduce the cost of global roaming for customers. Telstra and Optus have cut the price of their roaming packs and pay-as-you-go rates, while Vodafone has introduced an AU$5-per-day deal for travel in Europe, the US, the UK, and New Zealand.